This invention relates generally to systems for conditioning water and more particularly the systems for multiple conditioning of water by solids removal, dissolved contaminant removal, and temperature control.
In various industries there is a significant need for conditioned water meeting certain criteria for use within a product to be manufactured or for process needs, such as cooling, flushing, etc. For example, with respect to the Wire Electric Discharge Machine (WEDM) industry water of certain parameters, such as conductivity, maximum suspended particle size, etc., is needed to effect the operation of the machine. As is known a WEDM machine utilizes an electric current passed through a moving wire to a terminal in the path of a block of metal to be shaped or machined. The "shorting out" of the current results in the production of sparks which erodes a minute part of the metal, whereupon the metal is actually cut by the moving wire. With WEDM machines one is able to form intricate two and three dimensional shapes which could not heretofore be cut with difficult materials, such as hardened steel, etc. Inasmuch as the cutting action produces heat it is necessary to cool the work for dimensional control, to flush away contaminants, such as metal particles, suspended and dissolved contaminants, etc., and to permit a clear cutting path, while also insulating the workpiece so that the electrical sparks can be concentrated at the cutting edge and not stray into adjacent material. Thus, deionized water has been utilized for those purposes. In order to maintain the quality of the deionized water, equipment has been used to filter it, adjust its conductivity and control its temperature. Heretofore such conditioning has been accomplished piecemeal with little emphasis on measuring and controlling water conditions to meet changing demands of the WEDM machines.
In U.S. Pat. No. 3,928,163 (Ullmann, et al.) there is disclosed a WEDM machine having an associated system for conditioning water used therewith. To that end the Ullmann, et al. patent measures the quantity of used and stored water pumped from a storage tank back to the WEDM work. A conductivity controller located downstream of the storage tank controls the opening or closing of a solenoid valve directing used water, supplied by a separate pump, to a deionization or resin cartridge and back into the storage tank.
While the deionization system of the Ullmann, et al. patent does offer some advantages over the prior art by providing automatic deionization control taking into account changing conductivity levels of the water, it nevertheless suffers from various disadvantages. Thus, with the Ullmann system by the time that the conductivity sensor discovers that the water is less than the quality desired and directs the water to the resin bed for further treatment (i.e., deionization) it is already too late inasmuch as the water measured is already on its way to the WEDM machine. At best with the Ullmann system the water deionized by the measuring and controlling means may improve the quality of water still left in the storage tank after the measured water in the conduits has already flowed to the WEDM machine. Moreover, by monitoring the conductivity downstream of the water in the tank the water left in the tank without continuous treatment will normally degrade by air contamination so that it is not necessarily in the desired condition when it is ultimately pumped to the work. Moreover, unless contaminated water is properly prefiltered to remove a high percentage of solid contamination the life and effectiveness of the deionizing resin bed is substantially impaired, if not rendered useless.
Heretofore temperature control of the deionized water has been effected by the use of a heat exchanger installed directly in line to the WEDM machine. This arrangement requires large heat exchange equipment to provide temperature control over wide temperature ranges, thus possibly causing thermal distortion of the workpiece, the wire and the fixturing.
The prior art includes various patents utilizing a combined filter and deionization device within a single housing, such as U.S. Pat. Nos. 3,262,570 (Gailitis, et al.), 4,460,465 (Zacharkow, et al.) and 3,327,859 (Paul). However, such devices leave much to be desired from the standpoint of simplicity construction and the ability to select filtration without deionization or filtration with deionization. Accordingly, such prior art devices are not particularly suitable for use in a system for automatically conditioning water, such as in a WEDM system.
In view of the foregoing, a need presently exists for an integrated system, preferably modular, for effecting the automated multiple conditioning of water, that is, the removal of solid contaminants, dissolved contaminants and temperature control.